The von Hippel-Lindau (VHL) tumor suppressor gene on chromosome 3p25.5 is mutated in the majority of sporadic clear cell renal carcinomas and in VHL disease, an autosomal dominant familial cancer syndrome that predisposes affected individuals to a variety of tumors including clear cell renal carcinomas, cerebellar hemangioblastomas and hemangiomas, retinal angiomata, and pheochromocytomas. (Linehan, et al. 1995. “Identification of the von Hippel-Lindau (VHL) gene. Its role in renal cancer,” JAMA273:564-570; Gnarra, et al. 1996. “Molecular cloning of the von Hippel-Lindau tumor suppressor gene and its role in renal carcinoma,” Biochim Biophys Acta 1242;201-210; and Kaelin, W. G. and E. R. Maher. 1998. “The VHL tumor-suppressor gene paradigm,” Trends Genet 14:423-426). The VHL protein is expressed in most tissues and cell types and appears to perform multiple functions, including general repression of hypoxia-inducible genes (Iliopoulos, et al. 1996. “Negative regulation of hypoxia-inducible genes by the von Hippel-Lindau protein,” Proc Natl Acad Sci USA 93:10595-10599; Gnarra, et al. 1996. Post-transcriptional regulation of vascular endothelial growth factor mRNA by the product of the VHL tumor suppressor gene,” Proc Natl Acad Sci USA 93:10589-10594; and Siemeister, et al. 1996. “Reversion of deregulated expression of vascular endothelial growth factor in human renal carcinoma cells by von Hippel-Lindau tumor suppressor protein,” Cancer Res 56:2299-2301); regulation of p27 protein stability (Pause, et al. 1998. “The von Hippel-Lindau tumor suppressor gene is required for cell cycle exit upon serum withdrawal,” Proc Natl Acad Sci USA 95:993-998; and Kim, et al. 1999. “Recombinant adenovirus expressing Von Hippel-Lindau-mediated cell cycle arrest is associated with the induction of cyclin-dependent kinase inhibitor p27Kipl,” BBRC 253:672-677); and regulation of the assembly of extracellular fibronectin matrix (Ohh, et al. 1998. “The von Hippel-Lindau tumor suppressor protein is required for proper assembly of an extracellular fibronectin matrix,” Mol Cell 1:959-968).
In all cell types examined, the VHL protein is found in a multiprotein complex that includes the ubiquitin-like Elongin B protein, and Elongin C and the cullin CUL2, which share sequence similarity with the Skp1 and Cdc53 components of the Skp1-Cdc53p-F-box protein (SCF) ubiquitin ligase complex, respectively. (Kibel, et al. 1995. “Binding of the von Hippel-Lindau tumor suppressor protein to Elongin B and C,” Science 269:1444-1446; Duan, et al. 1995. “Inhibition of transcription elongation by the VHL tumor suppressor protein,” Science 269:1402-1406; Pause, et al. 1997. “The von Hippel-Lindau tumor-suppressor gene product forms a stable complex with human CUL-2, a member of the Cdc53 family of proteins,” Proc Natl Acad Sci USA 94:2156-2161; and Lonergan, et al. 1998. “Regulation of hypoxia-inducible mRNAs by the von Hippel-Lindau tumor suppressor protein requires binding to complexes containing Elongins B/C and Cul2,” Mol Cell Biol 18:732-741). Elongins B and C form a stable subcomplex that interacts with a short BC-box motif in the VHL protein and bridges its interaction with CUL2. (Pause, et al. 1997. Proc Natl Acad Sci USA 94:2156-2161; Lonergan, et al. 1998. Mol Cell Biol 18:732-741). A large fraction of VHL mutations found in sporadic clear cell renal carcinomas and in VHL kindreds result in mutation or deletion of the BC-box, disruption of the VHL complex, and deregulation of hypoxia-inducible gene expression, p27 protein stability, and bironectin matrix assembly. (Gnarra, et al. 1996. Biochim Biophys Acta 1242:201-210; Pause, et al. 1997. Proc Natl Acad Sci USA 94:2156-2161; Lonergan, et al. 1998. Mol Cell Biol 18:732-741; Ohh, et al. 1998. Mol Cell 1:959-968; and Kaelin, W. G. and E. R. Maher. 1998. Trends Genet 14:423-426).
Despite information currently available regarding the multiprotein complex that includes the VHL protein, Elongin B, Elongin C, and CUL2, not all components of this complex and the binding relationship of these components to one another have been elucidated. There is a continuing need to characterize yet unknown components of the complex and their interaction with other components to further the understanding of the complex and its relationship to disease.